Climate & Environment in the 9th century

21 sourced entries, 801 CE to 893 CE, oldest first. Also see Climate & Environment across every century or everything else in the 9th century.

• 801April 29 – Earthquake in Rome and Spoleto.source
• 803The 803 Mopsuestia earthquake takes place in the vicinity of Mopsuestia, and the Gulf of Alexandretta (İskenderun)source
• 824February – A major earthquake strikes Byzantium in Asia Minor (now part of western Turkey) and part of Greece, damaging the city walls of Theodosiopolis (now Barbaros in Turkey) and Heraclea Perinthus at the same time that the forces of Byzantine Emperor Michael II the Amorian are suppressing the rebellion by Thomas the Slav. Both cities surrender after the natural event.source
• 834The first mention is made of the Jona River ('the cold one') in Switzerland (approximate date).source
• 840June – The 840 Erzurum earthquake takes place in the city of Qaliqala (modern-day Erzurum in Turkey) (probable date).source
• 847November 24 – 847 Damascus earthquake.source
• 856November (approximate date) – An earthquake in Corinth, Greece kills an estimated 45,000 people.source
• 856December 3 – Another earthquake strikes the Abbasid Caliphate (modern-day Tunisia), also killing an estimated 45,000 people.source
• 856December 22 – Another earthquake strikes Damghan (modern-day Iran), killing an estimated 200,000 people.source
• 858An enormous flood along the Grand Canal inundates thousands of acres of farmland and kills tens of thousands of people in the North China Plain.source
• 859859 Syrian coast earthquake. It affected the Mediterranean coast of Syria It caused almost the complete destruction of Latakia and Jableh, major damage at Antioch and led to many deaths.source
• 859Winter – The weather is so severe that the Adriatic Sea freezes, and Italy is covered in snow for 100 days.source
• 86313 February – Dvin earthquake. It took place in the city of Dvin on 13 February, 863. During the 9th century, Dvin was the only "heavily populated" city in Muslim-dominated Armenia. The city was part of the wider Abbasid Caliphate, and had a multiethnic population.source
• 864Jōgan eruption (Japan): Mount Fuji, located on Honshu Island, erupts for 10 days.source
• 869July 9 – The 869 Sanriku earthquake and associated tsunami devastate a large part of the Sanriku coast on the northeastern side of the island of Honshu.source
• 869The Hagia Sophia Basilica (church) in Constantinople suffers great damage during an earthquake, which makes the eastern half-dome collapse. Basil I orders it to be repaired.source
• 874November – Frost begins in Scotland, and lasts until April 875.source
• 875Donyarth, the last recorded king of Cornwall, drowns in what is thought to be the River Fowey.source
• 881881 Acre earthquake: It takes place in the vicinity of Acre. Alexandria is reportedly affected by the same earthquake.source
• 893March 23 – 893 Ardabil earthquake. Several earthquake catalogues and historical sources describe this earthquake as a destructive earthquake that struck the city of Ardabil, Iran. The magnitude is unknown, but the death toll was reported to be very large. The USGS, in their "List of Earthquakes with 50,000 or More Deaths", give an estimate that 150,000 were killed, which would make it the ninth deadliest earthquake in history.source
• 893December 28 – An earthquake destroys the city of Dvin in Armenia.source